This report examines the variations on structural properties of $SnO_2$ thin films deposited by using thermal chemical vapor deposition techniques with different oxygen flow gas. TEM showed some of the interface to be atomically rough. The aspects of the boundary shape and growth behavior agree well with the theory of interface growth. The electron diffraction showed that the roughness was changed as the different oxygen flow gas increased. These measurement results suggested that the number of interface facet and abnormal grain growth were related oxygen flow gas.